Original Article
In-Vivo Force-Length Relationship of the Medial Gastrocnemius Muscle in Hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorders
Donald W. Golden1,2, Jason P. Oliemans1, Aera J.M. Ladell3,4, Kalindra D. Walls1, Eric C. Bennett1,5, Spencer J. Skaper1,6, Michael J. Asmussen7, Ranita H.K. Manocha2,4, Jared R. Fletcher1
1.
Department of Health and Physical Education, Mount Royal University, Calgary, AB Canada
2.
Cumming School of Medicine, University of Calgary. Calgary, AB Canada
3.
Department of Biology, Mount Royal University, Calgary, AB Canada
4.
Faculty of Kinesiology, University of Calgary. Calgary AB, Canada
5.
School of Health and Exercise Sciences, University of British Columbia. Kelowna BC, Canada
6.
Faculty of Medicine, University of British Columbia. Vancouver BC, Canada
7.
Department of Kinesiology, Faculty of Health Sciences and Human Service. Vancouver Island University. Nanaimo, BC Canada
Abstract
Objectives: To determine the force-length relationship, muscle thickness (MT), pennation angle (PA) and echo-intensity (EI) of the medial gastrocnemius (MG) in HSD/hEDS compared to healthy controls. Methods: The maximal MG force-length relationship was determined throughout ankle passive ROM in 11 individuals with HSD/hEDS and 11 healthy age- and sex-matched controls. MG fascicle length (FL), MT, PA and EI were measured using ultrasonography. MG force was calculated from plantarflexion moments and MG FL. Sarcomere lengths (SL) were estimated from changes in FL and assuming an optimal SL of 2.64 μm at optimal fascicle length. Results: HSD/hEDS were 36% weaker across the ankle ROM (p = 0.047). Optimal FL was significantly shorter in HSD/hEDS (34.8 ± 8.1 mm) compared to controls (43.6 ± 6.9 mm; p = 0.013). A shallower descending limb of the force-length relationship was seen in HSD/hEDS (p < 0.001). MT, PA, and EI were similar between groups (p > 0.05). Conclusion: HSD/hEDS were weaker at all measured fascicle lengths, despite similar muscle architecture (MT, PA) and quality (EI) suggesting that reduced neuromuscular activation may contribute to muscle weakness in this population. Rehabilitation interventions should consider addressing joint-angle specific strength deficits in HSD/hEDS.
Keywords
Ehlers-Danlos Syndrome Ehlers-Danlos Syndrome Joint Instability Joint Instability Muscle Strength Muscle Strength Muscle Weakness Muscle Weakness
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